MOUNT TENERIFFE
near North Bend, King County, Washington, USA
GEOLOGY
Intrusive Breccia - About 25 million years ago, near where Mount Teneriffe is today, magma associated with the Snoqualmie batholith intruded into older Tertiary marine sedimentary rock, fracturing and breaking up (brecciating) the rock as the magma intruded and the associated gasses escaped. Subsequent quartz mineralization from hydrothermal fluids filled the voids. The country rock north of Mount Teneriffe is specifically a marine argillite (formed from clay-rich marine sediment) that has been both brecciated and baked (thermally metamorhposed) by the intrusion.